High-Field Asymetric Waveform Ion Mobility Spectrometry (FAIMS) is a technology useful both for the separation of gas-phase ions at atmospheric pressure and room temperature as well as separation of gas phase ions over a wide range of temperatures and pressures.
In general, FAIMS is characterized by several features. These features include:
(1). Strong electric fields are used in FAIMS. Typically, FAIMS operates with fields greater then 5,000 volts/cm.
(2). In FAIMS a periodic asymmetric electric waveform is applied to conductive surfaces (e.g., plates) about 1-4 mm apart. The electric waveform is asymmetric which means that there is a significant difference between the peak +Ve and the peak −Ve voltage during the applied waveform. Either the +Ve or the −Ve may be the higher voltage.
(3). In FAIMS ions move through a gas in the electric field generated by the periodic asymmetric electric waveform. The gas is sufficiently dense that the ions rapidly reach a terminal velocity that is roughly proportional to the strength of the electric field. The velocity is compound dependent, permitting the separation of ion species from each other. The ions drift toward one of the plates as they travel in the electric field. Typically this drift may be stopped by applying a small DC voltage known as a compensation voltage (CV) which allows an ion specie of a selected mobility to pass through the field region to a detector.
A conventional FAIMS device permits sequential detection of different species of ions (e.g., ions having different mobilities) but does not provide for simultaneous analysis and/or detection of a plurality of ion species simultaneously.
Accordingly, there is a need for a FAIMS device and method for substantially simultaneous analyses and detection of a plurality of ion species.